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Thread: Exhaust restriction - later TD5 D2

  1. #1
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    Exhaust restriction - later TD5 D2

    As JC pointed out, there is a significant restriction in the bellows-type exhaust flexible joint that is in the later TD5 D2s, as was in my MY03 TD5. The opening is only 1.75", reducing the cross-sectional area of the 2.5" OD pipe to just 54%. There is now a mesh-type joint that has no internal obstructions. After only 1 outing, I feel that the engine is smoother under medium throttle at lower to medium revs. Where I previously ran between successive tight roundabouts in 3rd, 3rd was only used for a few seconds whilst negotiating the roundabouts then 4th pulled well until the next one. I have a test section of road that heads uphill after a roundabout in an 80 zone and I was able to get to 5th earlier and with much less fuss than previously, still heading uphill.

    The annoying exhaust reverberation is gone, which was the reason for the change.
    MY21.5 L405 D350 Vogue SE with 19s. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi, RTK base station using LoRa

  2. #2
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    Graeme,
    Where can you get the mesh type joint and how much? Part numbers too please.

    Mundy

  3. #3
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    As a wise man once said - "It didn't happen if there are no photos"

  4. #4
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    The mesh type joint is actually the "earlier" type and are a LOT more prone to failing / splitting, the modified / updated later one is the "bellows" type as you called it. Both types provide a good flow for discoveries, removing the cat on later ones would be a better option imo to "Improve" performance.

  5. #5
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    If the bellows type reduces the internal cross sectional area by 50% how can it still be providing good clow compared to the mesh type that maintains a full diameter throughout.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  6. #6
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    Quote Originally Posted by Mundy View Post
    Graeme,
    Where can you get the mesh type joint and how much? Part numbers too please.

    Mundy
    Purchased from Macperformance.com through e-bay. Its the 2.5" x 6" version (overall length but considerably longer than the one on the early D2s so might last longer) and cost $12.50 US which converted to around A$60 incl postage. I cut out the bellows and tack-welded the new one in place then had the joins mig-welded locally for a neat job for $16. The length very nicely allows the reduced sections of pipe above and below the bellows unit to be cut out totally. An exhaust shop had quoted $150 plus fitting.

    The bellows were fully extended and pulled down against the internal stop by the weight of the rest of the exhaust system and IMO this would have been causing the vibrations and cabin drone that I've been chasing for around 18 months.

    There is a significant/major improvement in response to light and heavier throttle and to engine smoothness. Yesterday afternoon I re-installed the harmonic balancer that was removed some time ago with the idea of cleaning-up the last remains of what had been a bad vibration around 2500-2600 rpm, but after today's driving that's coming off again as some drone returned.
    MY21.5 L405 D350 Vogue SE with 19s. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi, RTK base station using LoRa

  7. #7
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    The restriction can be seen in this picture.
    Attached Images Attached Images
    MY21.5 L405 D350 Vogue SE with 19s. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi, RTK base station using LoRa

  8. #8
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    What were they thinking when they changed to that!
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  9. #9
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    Thanks for bringing this up again Graeme. BTW, I have seen way more bellows ones vibrate and fail than the mesh type. I just fitted another one recently, about $90 for the 2.5" stainless flex, and the whole job took less than an hour, including removal and refitting of crossmembers etc.

    Again, smoother, vibrationless Td5 D2 = people.

    JC
    The Isuzu 110. Solid and as dependable as a rock, coming soon with auto box😊
    The Range Rover L322 4.4.TTDV8 ....probably won't bother with the remap..😈

  10. #10
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    Quote Originally Posted by Urban Panzer View Post
    The mesh type joint is actually the "earlier" type and are a LOT more prone to failing / splitting, the modified / updated later one is the "bellows" type as you called it. Both types provide a good flow for discoveries, removing the cat on later ones would be a better option imo to "Improve" performance.
    I have 200,000ks on my TD5 without any problems with my flex joint, trust me this Disco gets a hard time

    I had a look at one of those later bellows type joints, they look very restrictive compared the the early flex joint.

    Mundy any muffler place have them for $60, i just paid $145 for a 3" flex, 1mtr of straight 3", 1 3" mandrel bend 2, 3 hole 3" flanges and gaskets and 1 2 hole 3" flange.

    Best Mufflers in Hurstville is a good place to get them.

    Going 3" back to the second muffler

    Baz.
    Cheers Baz.

    2011 Discovery 4 SE 2.7L
    1990 Perentie FFR EX Aust Army
    1967 Series IIa 109 (Farm Truck)
    2007 BMW R1200GS
    1979 BMW R80/7
    1983 BMW R100TIC Ex ACT Police
    1994 Yamaha XT225 Serow

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